I'm the same, but I've always regarded this as luck rather than logic.
I think some people have a 'switch' thrown in their brain where they become vulnerable to suicidal ideas. It's often, but not always, part of mental illness. A depressive might think 'I am unworthy to live' or 'life is nothing but pain'. An anorexic may get 'I care more about my weight than maintaining my life'. A schizophrenic may find their voices are shouting endlessly that they 'need' to die. An OCD/anxiety sufferer may get so tired of their endless pointless struggle with their own rituals they wish everything was over. Sadly, none of this is susceptible to reason. The trouble with mental illness and suicide is essentially that the toolkit one is using to validate perceptions and make decisions may have gone haywire. And it's not always easy to spot when a form of pseudo-rationality has taken over. I met one depressive who decided calmly and rationally that his daughters would have a better life without him, and only lived because he rang 999 at the last minute. When I met him in mental hospital he was bemused by the fact that such an irrational decision could have seemed so rational. He couldn't, in his current state of comparative mental health, understand how he could have thought that way. To his sane self it was patently obvious that if he'd succeeded it would have caused his daughters pain rather than benefit.
And it's possible for the sake of argument to imagine a situation where suicide might be a rational response. If somebody is terminally ill, with no prospect of ever getting better, and in constant pain, does it then sound a reasonable response? Or somebody with locked-in syndrome who can't move a muscle? I suppose both those possibilities might make me think 'what is the person being kept alive <I>for</I>?' The practical problem might be that it's only at the point where the person's autonomy is severely compromised when it becomes thinkable. And I'd support keeping people alive where their quality of life is significantly constrained from the able-bodied norm, it's just I can imagine situations where it might be reasonable not to.
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I feel tempted to add that you, in your Aspie rationality, may benefit from reading the blog 'You're Not So Smart'. No, I'm not trying to imply I'm brighter than you, or even that the blog writer is brighter than both of us. It's just an interesting blog for picking up the points where we (all us humans) blithely take a step away from the rational thought we still think we're firmly attached to. I find this sadly persuasive. It occurred to me a long time ago that logic is 'that part of the brain with which we think we think'. I'm an Aspie rationalist myself, and I have to remind myself sometimes that none of us is a conspicuous example of logic and reason in the whole of our lives.